Filter

ABSTRACT

This filter is used for purifying air by removing foreign matters such as liquid droplets contained in the air. A separation unit is formed by a primary port, a port block to which a secondary port is formed, and a separation cylinder attached to the port block. Inside a swirl flow generating chamber of the separation unit, a cylinder blade portion formed by arranging a plurality of blades, which are extended in an axial direction along an inner peripheral surface and also inclined in a circumferential direction, in a cylindrical form is provided. The air flowed into the swirl flow generating chamber is caused to be a swirl flow by the cylindrical blade portion and foreign matters such as liquid droplets are discharged toward a collection container in a separation chamber. The purified air is guided from a discharge pipe to the secondary port.

TECHNICAL FIELD

The present invention relates to a filter which is used to removeforeign matters, such as liquid droplets or dusts, from air to besupplied into a pneumatic device.

BACKGROUND ART

A pneumatic device, such as a pneumatic cylinder, is supplied with airfrom a pneumatic source via a pneumatic line such as piping or hose. Byconnecting the pneumatic source and the pneumatic device via thepneumatic line, a pneumatic circuit is formed. Air to be supplied fromthe pneumatic source to the pneumatic device is handled as air to betreated, and the pneumatic circuit is provided with a filter forremoving foreign matters, such as water droplets or oil droplets ordusts, contained in the air to be treated.

As one type of the filter provided in the pneumatic circuit, PatentDocument 1 discloses a filter having a main block, that is, a port blockformed with a primary port and a secondary port, and a filter elementattached to the port block. The filter element is adapted to removeforeign matters being composed of liquid droplets such as water dropletsor dusts such as powdery and granular materials which are contained inthe air to be treated and flowing from the primary port, and todischarge the purified air to the secondary port. In order to receivethe foreign matters such as liquid droplets removed by the filterelement, a filter bowl, namely, a collection container is attached tothe port block.

As a filter to be used in the pneumatic circuit, forms being called airfilter, mist filter, and micro mist filter are known, and these filtersare defined according to foreign matter removal performance set on thebasis of an inner diameter of air holes of a filter element or the like.

A filter adapted to swirl liquid to remove foreign matters mixed inliquid coolant is disclosed in Patent Document 2. This filter is adaptedto swirl liquid to remove foreign matters from liquid on the basis ofthe differences in specific gravity and centrifugal force between theliquid and foreign matters.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Patent Application Laid-Open Publication    No. H07-328364-   Patent Document 2: Japanese Patent Application Laid-Open Publication    No. 2011-51055

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

To remove foreign matters by swirling the air containing foreign mattersusing a difference in centrifugal force of the air and the foreignmatters, the air is blown out into a swirling chamber having acylindrical shape from an air supply port in a tangential direction. Itis difficult to reliably remove foreign matters in compressed airsupplied into a pneumatic circuit by using such a foreign-matterremoving method. This is because, as a large number of pneumaticequipment is incorporated in a pneumatic circuit in an assembly plant ofelectronic parts, the flow velocity of the air flowing in the pneumaticcircuit is largely fluctuated depending on an operation state of thepneumatic equipment.

When a filter using centrifugal force is used to purify the air suppliedinto the pneumatic circuit in which the flow velocity may be largelyfluctuated, centrifugal force applied on foreign matters is low when theflow velocity is low and it causes foreign matters such as liquiddroplets to flow out from an air outflow port; thus, the processed aircannot be sufficiently purified. To prevent foreign matters fromentering the air outflow port, it is required to make the inner diameterof the swirling chamber large, but it makes the filter to belarge-sized. On the other hand, when the setting is such that the flowrate is low and a filter element is used for enhancing the separationeffect, the more the flow velocity is increased, the lower theseparation efficiency becomes; thus, it is required to make a flow-patharea large for lowering the flow velocity and thus a size increase ofthe filter is unavoidable.

A preferred aim of the present invention is to separate and removeforeign matters such as liquid droplets contained in the air by using asmall-sized filter.

Means for Solving the Problems

A filter according to the present invention is a filter for purifyingthe air by removing foreign matters such as liquid droplets or dustscontained in the air, the filter including: a port block provided with aprimary port to which the air is supplied and a secondary port thatcauses purified air to flow out; a separation cylindrical unit providedto the port block to form a separation unit together with the port blockand to form a swirl flow generating chamber having a cylindrical shapecommunicated with the primary port and a separation chambercommunicating with the swirl flow generating chamber in the separationunit; a discharge pipe positioned at a central portion of the swirl flowgenerating chamber to guide purified air to the secondary port; and acylindrical blade portion formed by arranging a plurality of blades in acylindrical form, each of which extends in an axial direction along aninner peripheral surface of the swirl flow generating chamber andinclines in the circumferential direction, the filter swirling the airsupplied from the primary port and inflowing into the swirl flowgenerating chamber in the axial direction for removing the foreignmatter by causing the foreign matters contained in the air attached tothe inner peripheral surface of the separation cylindrical unit.

The filter according to the present invention has a feature in causingthe cylindrical blade portion swirl the air supplied from the primaryport while flowing the air inward in a diameter direction. The filteraccording to the present invention has a feature in causing thecylindrical blade portion swirl the air supplied from the primary portwhile flowing the air outward in the diameter direction.

The filter according to the present invention has a feature inincluding: an annular base portion fitted with the inner peripheralsurface of the separation unit arranged at a lower end of thecylindrical blade portion; and a closing lid portion arranged betweenthe discharge pipe and an upper end of the cylindrical blade portion.The filter according to the present invention has a feature in includingan annular base portion arranged at the lower end portion of thecylindrical blade portion and fixed to the discharge pipe; and a closinglid portion arranged between the inner peripheral surface of theseparation unit and the upper end of the cylindrical blade portion. Thefilter according to the present invention has a feature in integrallyforming the cylindrical blade portion and the annular base portion.

The filter according to the present invention has a feature in forming anotched portion at an upper end portion of each of the blades andfitting the closing lid portion with the notched portion. The filteraccording to the present invention has a feature in forming a liquiddroplet discharge groove between an outer peripheral surface of theannular base portion and the separation unit. The filter according tothe present invention has a feature in forming, to an upper surface ofthe annular base portion, a first liquid droplet guiding surfacegradually inclined downward in a radially-inward direction so that theliquid droplet attached to the upper surface of the annular base portionis dropped downward by the first liquid droplet guiding surface. Thefilter according to the present invention has a feature in forming thelower surface of the closing lid portion in a perpendicular direction toa center axis of the separation unit from an outer peripheral portion toan inner peripheral portion or forming the lower surface of the closinglid portion inclined downward below the perpendicular direction from theouter peripheral portion to the inner peripheral portion.

Effects of the Invention

According to the present invention, in the separation unit including theswirl flow generating chamber having the cylindrical shape and theseparation chamber, a swirl flow is generated by the air supplied fromthe primary port to the swirl flow generating chamber in the axialdirection by the cylindrical blade portion inside the swirl flowgenerating chamber; thus, the swirl flow is formed toward the separationchamber by the whole of the circumferential direction of the cylindricalblade portion. In this manner, without increasing the inner diameter ofthe swirl flow generating chamber, a swirl flow can be generated andforeign matters such as water droplets contained in the air can beremoved, thereby obtaining a small-sized filter excellent in separationperformance.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a cross sectional view showing a filter according to oneembodiment of the present invention;

FIG. 2 is an enlarged sectional view showing the upper half of thefilter shown in FIG. 1;

FIG. 3 is an enlarged sectional view showing the lower half of thefilter shown in FIG. 1;

FIG. 4 is a cross sectional view taken along the line A-A in FIG. 1;

FIG. 5 is a cross sectional view taken along the line B-B in FIG. 1;

FIG. 6 is a cross sectional view taken along the line C-C in FIG. 1;

FIG. 7 is a cross sectional view taken along the line D-D in FIG. 1;

FIG. 8 is an exploded perspective view showing the swirl flow generatorshown in FIGS. 1 and 2;

FIG. 9 is an exploded perspective view showing the filter;

FIG. 10 is an exploded perspective view showing a collection containerand an annular lock member;

FIG. 11 is a cross sectional view showing the upper half of a filteraccording to another embodiment of the present invention;

FIG. 12 is a perspective view of FIG. 11; and

FIG. 13 is an exploded perspective view showing a swirl flow generatorshown in FIGS. 10 and 11.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings. As shown in FIG. 1, a filter 10has a port block 13 made of metal and formed with a primary port 11 anda secondary port 12. The primary port 11 is connected to a primary airpressure line composed of a piping not shown or the like, and air froman air pressure source is supplied to the primary port 11 via the airpressure line. The secondary port 12 is connected to a secondary airpressure line composed of a piping not shown or the like, and purifiedair from which liquid droplets and the like are removed is supplied toan external pneumatic device from the secondary port via the airpressure line. The primary port 11 and the secondary port 12 arecoaxially opened at side surfaces of the port block 13 opposite to eachother, respectively. Side surfaces of the port block 13 from which therespective ports are opened are formed in an approximately flat shape,and the port block 13 has a shape close to a cubic shape as a whole, asshown in FIG. 9.

The port block 13 is formed with a receiving hole 14 therein, and theprimary port 11 is in communication with the receiving hole 14. Asupporting portion 16 formed with a communication hole 15 is provided toa central portion of the port block 13, and air supplied to the primaryport 11 flows to a lower portion of the receiving hole 14 via acommunication space between the supporting portion 16 and the receivinghole 14.

A lower end portion of the port block 13 is provided with a cylindricalmale screw portion 17. A separation cylinder 20 made of resin isdetachably attached to the male screw portion 17, and an upper endportion of the separation cylinder 20 is provided with a female screwportion 18 which is screwed to the male screw portion 17. The separationcylinder 20 has a cylindrical portion 21 having a constant innerdiameter, and a conical portion 22 continuously extending downward froma lower portion of the cylindrical portion 21 and having an innerdiameter gradually reduced toward a lower end portion thereof. Aseparation unit 23 is composed of the port block 13 and the separationcylinder 20 attached to this block. The separation unit 23 is formedtherein with an upper side swirl flow generating chamber 24 and a lowerside separation chamber 25 which communicate with each other. Theseparation unit 23 shown in this figure is configured so that the swirlflow generating chamber 24 is formed of the port block 13 and theseparation cylinder 20, but it may be configured so that the swirl flowgenerating chamber 24 is formed of the port block 13 and the separationchamber 25 is formed of the separation cylinder 20, or it may beconfigured so that the swirl flow generating chamber 24 and theseparation chamber 25 are formed in the separation cylinder 20.

The conical portion 22 of the separation cylinder 20 is provided with amale screw portion 26, and the male screw portion 26 is the same in anouter diameter as the male screw portion 17 of the port block 13. Acollection container 27 is detachably attached to the male screw portion26. The collection container 27 has a cylindrical portion 28 a and abottom wall portion 28 b integral with the cylindrical portion 28 a, andis made of a transparent material. An upper end portion of thecollection container 27 is provided with a female screw portion 29 whichis screwed to the male screw portion 26. The female screw portion 29 isthe same in an inner diameter as the female screw portion 18 of thecylindrical portion 21 of the separation cylinder 20. The collectioncontainer 27 is formed with a storage chamber 30 in which foreignmatters such as liquid droplets are received, and the inside of theseparation cylinder 20 and the storage chamber 30 are in communicationwith each other via a discharge port 31 formed at a lower end portion ofthe separation cylinder 20.

A swirl flow generator 32 made of resin is attached in the swirl flowgenerating chamber 24 of the separation unit 23. The swirl flowgenerator 32 has an annular base portion 33 which is fitted to an innerperipheral surface of the cylindrical portion 21 of the separationcylinder 20. The annular base portion 33 is integral with a cylindricalblade portion 34. As shown in FIGS. 2 and 4, the cylindrical bladeportion 34 is provided with a plurality of wings, that is, blades 35extending in an axial direction along an inner peripheral surface of thereceiving hole 14, that is, an inner peripheral surface of the swirlflow generating chamber 24, and the blades 35 are formed and arranged ina cylindrical shape respectively at intervals of clearances 36. As shownin FIG. 4, each of the blades 35 has an inclination angle to atangential line to the inner peripheral surface of the cylindrical bladeportion 34. By providing the inclination angle in this manner, flow ofair is changed to swirling flow. In addition, since many blades 35 arearranged over a whole circumference of the cylindrical blade portion 34and have lengths in the axial direction, swirling flow can be obtainedefficiently with a low pressure loss though the cylindrical bladeportion 34 is thin in a radial direction. The cylindrical blade portion34 is composed of twenty-one blades 35. As shown in FIG. 4, therespective blades 35 are set that wall thicknesses thereof on a radiallyinner side are thinner than those thereof on a radially outer side, andeach clearance 36 formed between the respective blades extends along thecentral axis of the separation unit 23 in an axial direction andinclines in a circumferential direction.

A discharge pipe 37 is attached in the communication hole 15, and alower end surface of the discharge pipe 37 extends beyond thecylindrical blade portion 34 downward to reach the position of theannular base portion 33. Air purified by separation of foreign mattersis guided to the secondary port 12 via the discharge pipe 37. Thedischarge pipe 37 is integral with a closing lid portion 38, and thisclosing lid portion 38 is arranged at the upper end portions of thecylindrical blade portion 34. Air flowing from the primary port 11 intothe receiving hole 14 is prevented by the closing lid portion 38 fromflowing into the cylindrical blade portion 34 from a radial inner sideof the cylindrical blade portion 34.

Thus, the swirl flow generator 32 is composed of the cylindrical bladeportion 34 formed into a cylindrical shape as a whole, the annular baseportion 33 arranged at the lower end portion of the cylindrical bladeportion 34 and fitted into the inner peripheral surface of thecylindrical portion 21 of the separation cylinder 20, and the closinglid portion 38 arranged at the upper end portions of the cylindricalblade portion 34 and the discharge pipe 37. Therefore, air supplied fromthe primary port 11 into the receiving hole 14 flows in the swirl flowgenerating chamber 24 in the axial direction to flow from an upper outerperipheral surface of the cylindrical blade portion 34 into theclearances 36 among the blades 35. Air flowing in the respectiveclearances 36 is guided by the blades 35 to be jetted toward the insideof the cylindrical blade portion 34 in an inclined manner to thetangential direction. Therefore, swirling flow of air is produced insidethe cylindrical blade portion 34, and the swirl flow flows into thelower-side separation chamber 25 in the separation cylinder 20 whilebeing swirled. When the air flow is changed to the swirl flow, acentrifugal force applied to liquid droplets having a specific gravitylarger than air is larger than that applied to air, so that the liquiddroplets adhere to an inner peripheral surface of the conical portion22. The liquid droplets adhered to the inner peripheral surface dropfrom the discharge port 31 into the storage chamber 30.

As described above, the cylindrical blade portion 34 formed by arrangingthe blades 35 in the cylindrical shape is integrated with the annularbase portion 33, and the closing lid portion 38 integrated with thedischarge pipe 37 is fitted into a distal end portion of the cylindricalblade portion 34. However, the cylindrical blade portion 34 and theclosing lid portion 38 may be integrated with each other, and theannular base portion 33 may abut on the lower end surface of thecylindrical blade portion 34. Furthermore, the discharge pipe 37 and theclosing lid portion 38 are integrated with each other. However, thesemembers may be separated from each other.

As shown in figures, air flowed from the primary port 11 into the swirlflow generating chamber 24 flows from an outer peripheral portion of theswirl flow generating chamber 24 to the swirl flow generator 32 in theaxial direction so that axial flow is changed into swirl flow by theblades 35. Since twenty-one blades 35 are arranged over the wholecircumference of 360 degrees, inflow air is applied with a swirlingforce over the whole circumference of 360 degrees. Therefore, ascompared with a case where air is caused to flow from an intake port toan inner peripheral surface of the separation cylinder 20 in atangential direction as disclosed in Patent Document 2, a high speedswirl flow can be produced efficiently without making the inner diameterof the separation cylinder 20 large. Accordingly, the filter which formsswirl flow to remove liquid droplets contained therein can be made smallin size.

The separation cylinder 20 has the cylindrical portion 21 and theconical portion 22 positioned at the bottom of the cylindrical portion21, and the centrifugal force acting on swirl flow produced by the swirlflow generator 32 can be prevented from being attenuated at the conicalportion 22. Therefore, when the lower portion of the separation cylinder20 is formed in a conical shape, a separation efficiency of foreignmatters due to adhesion of foreign matters such as liquid droplets tothe inner peripheral surface can be made higher than that in such anaspect that the whole separation cylinder 20 is formed in a cylindricalshape. Air purified by removing foreign matters rises while beingswirling to flow into the discharge pipe 37, and is discharged from thesecondary port 12 to outside.

Notched portions 39 are formed on a radially-inner side of the upper endportion of the cylindrical blade portion 34. As shown in FIG. 4, aninner diameter of the notched portions 39 corresponds to an outerdiameter R of the lower end portion of the closing lid portion 38, sothat the closing lid portion 38 is fitted into the notched portions 39.Since the closing lid portion 38 is fitted into the inside of the upperend portion of the cylindrical blade portion 34 in this manner, therespective blades 35 are prevented from being deformed radially inward.A portion of an outer peripheral surface of the closing lid portion 38located from a portion thereof above the upper end surface of thecylindrical blade portion 34 to the supporting portion 16 is formed as ataper surface 41 having a diameter reduced upwardly. Therefore, airflowed from the primary port 11 into the swirl flow generating chamber24 is guided radially outward by the taper surface 41, then flows alongthe inner peripheral surface of the cylindrical blade portion 34 whileflowing downward from the clearances 36 between the closing lid portion38 and the receiving hole 14 along the respective blades 35, resultingin swirl flow of the flowed-in air.

A lower surface 42 of the closing lid portion 38 is formed in a flatsurface extending from an outer peripheral portion to an innerperipheral portion so as to be at a right angle to the central axis ofthe closing lid portion 38 so that liquid droplets contained in theswirl flow do not adhere to the lower surface 42. Therefore, liquiddroplets flowed together with air from the outer periphery of theclosing lid portion 38 into the cylindrical blade portion 34 flowdownward together with the swirl flow without adhering to the lowersurface 42. According to an experiment, when the lower surface 42 isformed in an upwardly-inclined surface extending from the radially outerportion toward the radially inner portion, liquid droplets adhere to thelower surface 42. Furthermore, when the lower surface is formed with anannular groove, liquid droplets are captured in the annular groove, andtherefore, the liquid droplets cannot be smoothly dropped. On the otherhand, as shown in FIGS. 1 and 2, when the lower surface 42 is formed ata right angle to the central axis or when it is inclined downward fromthe radially outer portion toward the central portion as shown by atwo-dot chain line 42 a in FIG. 2, liquid droplets are prevented fromadhering to the lower surface 42.

A clearance 43 is formed between the inner peripheral surface of thereceiving hole 14 and the outer peripheral surface of the cylindricalblade portion 34. Liquid droplets mixed in air to be flowed from theprimary port 11 into the swirl flow generating chamber 24 are partiallyguided by the clearance 43 between the blades 35 and the innerperipheral surface of the receiving hole 14 to flow to the lower endportions of the blades 35. As shown in FIG. 2, as part of an uppersurface of the annular base portion 33, a second liquid droplet guidingsurface 44 inclined downward as going radially outward is formed on theoutside of the outer diameter of the cylindrical blade portion 34. Asshown in FIG. 5, a plurality of liquid discharge grooves 45 are formedon an outer peripheral surface of the annular base portion 33, andliquid droplets which has flowed to reach the outermost peripheralportion of the second liquid droplet guiding surface 44 are guided fromthe respective liquid discharge grooves 45 to a lower portion of theseparation cylinder 20. On the other hand, as part of the upper surfaceof the annular base portion 33, a first liquid droplet guiding surface46 inclined downward as going radially inward is formed between theouter peripheral surface and the inner peripheral surface of thecylindrical blade portion 34.

Therefore, liquid droplets which have flowed downward via the clearances36 among the blades 35 to reach the upper surface of the annular baseportion 33 are dropped downward from the minimum diameter portion of theinclined first liquid droplet guiding surface 46. In this way, amongliquid droplets such as water droplets and oil droplets which flowtogether with air from the primary port 11 into the swirl flowgenerating chamber 24, liquid droplets flowed between the outerperipheral surface of the cylindrical blade portion 34 and the receivinghole 14 are guided by the second liquid droplet guiding surface 44, andthen guided from the liquid discharge grooves 45 to the inner peripheralsurface of the separation cylinder 20. Therefore, they can be securelyprevented from entering the discharge pipe 37. In particular, even if anamount of air supplied to the primary port 11 is rapidly increased,liquid droplets can be securely prevented from being captured in thedischarge pipe 37. On the other hand, liquid droplets dropped along theblades 35 down to the first liquid droplet guiding surface 46 are guidedby the first liquid droplet guiding surface 46 to drop below the annularbase portion 33, so that liquid droplets can be securely prevented frombeing captured in the discharge pipe 37. As shown in FIG. 5, the numberof liquid discharge grooves 45 provided is four, but the number may beset to an arbitrary number. Furthermore, the liquid discharge grooves 45may be formed on the inner peripheral surface of the cylindrical portion21.

A lower surface of the annular base portion 33 is formed as a tapersurface 47 inclined downward so that an inner diameter thereof becomeslarger from the minimum diameter portion of the first liquid dropletguiding surface 46 to the outer peripheral surface of the annular baseportion 33. As described above, when the lower surface of the annularbase portion 33 is formed as a diameter-enlarged portion expandeddownward so that an inner diameter of the lower surface becomes largerdownward, namely as the taper surface 47, air guided by the blades 35 tobe changed to swirl flow is guided to the separation chamber 25 of theseparation cylinder 20 while a swirling radius thereof becomes largertoward the taper surface 47. The lower end surface of the discharge pipe37 is set to be the same axial position as that of the annular baseportion 33, and a radially outer side of the lower end portion of thedischarge pipe 37 corresponds to the annular base portion 33, but aninner surface of the annular base portion 33 is formed as such a tapersurface 47 that an inner diameter thereof becomes larger downward, sothat liquid droplets adhered to the taper surface 47 can be securelyprevented from being captured into the discharge pipe 37. In particular,even if an amount of inflow air from the primary port 11 is rapidlyincreased, liquid droplets can be prevented from being captured in thedischarge pipe 37.

In such a case that a distance between the inner peripheral surface ofthe annular base portion 33 and the outer periphery of the dischargepipe 37 is short, if the inner peripheral surface of the annular baseportion 33 is made straight, there is such a possibility that liquiddroplets are captured into the discharge pipe 37, but liquid dropletscan be securely prevented from entering the discharge pipe 37 by formingthe inner peripheral surface as the taper surface 47. Thediameter-enlarged portion formed on the annular base portion 33 is notlimited to the taper surface. If an inner diameter is set to be largerthan the inner diameter of the cylindrical blade portion 34, even if adiameter-enlarged portion having a straight inner diameter is adopted,it can prevent liquid droplets from being captured into the dischargepipe 37.

Air flowed from the taper surface 47 into the separation chamber 25 andswirled along the inner peripheral surface of the cylindrical portion 21is guided and swirled by the inner peripheral surface of the conicalportion 22, namely a conical surface 48, having the inner diameterbecoming smaller toward the lower end portion. In air flowing along theconical surface 48, centrifugal force generated is maintained, andliquid droplets contained in the air adhere to the conical surface 48 ofthe conical portion 22 to flow toward the discharge port 31 at the lowerend portion.

As described above, by forming the second liquid droplet guiding surface44 on a portion of the upper surface of the annular base portion 33positioned radially outside and forming the first liquid droplet guidingsurface 46 on a portion of the upper surface of the annular base portion33 positioned radially inside, liquid droplets flowed down to the uppersurface of the annular base portion 33 can be securely dropped downward.

A baffle plate 51 provided with a liquid guiding surface 50 opposed tothe discharge port 31 is disposed in the collection container 27. Asshown in FIG. 3, liquid droplets dropped from the discharge port 31 stayon the bottom of the storage chamber 30, and liquid droplets on thebottom of the storage chamber 30 are prevented from flowing back intothe separation chamber 25 due to cyclone effect of the swirl flow, sincethe baffle plate 51 is opposed to the discharge port 31 via a clearanceof a baffle arrangement distance L. Eight fins 52 extending in a radialdirection of the liquid guiding surface 50 and projecting upward,respectively, are provided radially on the liquid guiding surface 50 ofthe baffle plate 51, as shown in FIGS. 3 and 6. Thus, air in the storagechamber 30 is prevented from being swirled in accordance with airswirled in the discharge port 31 by the plurality of radial fins 52.Thus, liquid in the storage chamber 30 is prevented by the baffle plate51 provided with fins 52 from being whirled up by the cyclone effect dueto swirling of air in the storage chamber 30 and being flowed out to thesecondary port 12. Furthermore, air swirled downward along the conicalsurface 48 is reflected by the baffle plate 51 in a reverse directionand moved upward toward the discharge pipe 37.

The baffle plate 51 is integrated with a base plate 53 which is locatedjust below the baffle plate 51, and which has a diameter larger thanthat of the baffle plate 51. As shown in FIG. 7, a cross-shaped legportion 54 is attached to the base plate 53 via a coupling portion 53 ashown in FIG. 3. The leg portion 54 includes four plate-like membersextending radially from a radial central portion of the leg portion 54.The leg portion 54 is composed of two large-diameter plates 54 bextending near the inner peripheral surface of the collection container27 and having a notch hole 54 a near the axial center of the leg portion54 and two small-diameter plates 54 c having a large clearance betweenthe inner peripheral surface of the collection container 27 and each ofthe small-diameter plates 54 c. Therefore, air is securely preventedfrom being swirled in the storage chamber 30. A coupling portion 55provided at the lower portion of the leg portion 54 is assembled in adischarge hole 56 formed in a bottom wall portion 28 b of the collectioncontainer 27, and a discharge pipe 57 inserted into a lower side of thedischarge hole 56 is coupled to the coupling portion 55. The dischargepipe 57 is engaged with a cam portion of an operation knob 58 rotatablyattached on an outer periphery of a discharge port 28 c provided on thebottom wall portion 28 b, so that the discharge pipe 57 is movedvertically by operating the operation knob 58 in a rotating manner. Whenthe discharge pipe 57 is moved upward by the operation knob 58, a sealmember 59 a provided on the coupling portion 55 is separated from thebottom wall portion 28 b. Therefore, liquid in the storage chamber 30 isdrained outside via the discharge pipe 57.

As shown in FIG. 3, when the inner diameter of the discharge port 31 ofthe separation cylinder 20 is represented as “D” and an conical angle ofthe conical portion 22 of the lower end portion of the separationcylinder 20 is represented as “θ”, the inner diameter D and the conicalangle θ are set to 6.5 to 9 mm and 20 to 30 degrees, respectively.Therefore, it is confirmed that liquid droplets could be caused toadhere to the inner surface of the conical portion 22 and the adheredliquid droplets could be drained from the discharge port 31 to thestorage chamber 30, so that a liquid droplets removal effect could beenhanced.

When a surface angle of the liquid guiding surface 50 of the baffleplate 51 is represented as a and a baffle arrangement distance betweenthe discharge port 31 and the liquid guiding surface 50 is representedas L, the surface angle α and the baffle arrangement distance L are setto 90 to 180 degrees and 5 to 15 mm, respectively. Therefore, liquiddroplets dropped downward from the discharge port 31 are securelyprevented from moving upward and flowing back into the separationchamber 25. When the baffle arrangement distance L is set to be shorterthan 5 mm, there is a possibility that liquid droplets adhered to theliquid guiding surface 50 of the baffle plate 51 flows back into theseparation cylinder 20. On the contrary, when the baffle arrangementdistance L is set to be larger than 15 mm, there is such a possibilitythat liquid droplets passed through the discharge port 31 stay on theliquid guiding surface 50, and the liquid droplets stayed are movedupward and scattered by the cyclone effect due to change of a flow rateor the like so that they flow back from the discharge port 31 into theseparation cylinder 20. Regarding the surface angle α, liquid dropletscan be securely prevented from flowing back from the baffle plate 51 bysetting the surface angle α to the above-described angle range.

As shown in FIG. 1, on an outside of the female screw portion 18 of theseparation cylinder 20, an annular lock member 63 made of resin ismovably attached in the axial direction in order to lock a state wherethe separation cylinder 20 is fastened to the male screw portion 17 ofthe port block 13 and release the lock state performed when theseparation cylinder 20 is detached from the port block 13. Similarly, onan outside of the female screw portion 29 of the collection container27, an annular lock member 64 made of resin is movably attached in theaxial direction in order to lock a state where the collection container27 is fastened to the male screw portion 26 of the separation cylinder20 and release the lock state performed when the collection container 27is detached from the separation cylinder 20. The respective annular lockmembers 63 and 64 have the same structure as each other.

FIG. 10 is an exploded perspective view of the collection container 27and the annular lock member 64, where two convex guide portions 65 areprovided on an outer peripheral surface of the collection container 27so as to be shifted from each other by an angle of 180° in acircumferential direction, and a concave guide portion 66 in which theconvex guide portion 65 is inserted is formed on an inner peripheralsurface of the annular lock member 64, as shown in FIG. 10. Therefore,the annular lock member 64 is moved outside the collection container 27in the axial direction while being guided by the convex guide portions65 inserted into the concave guide portions 66. Outer surfaces ofportions of the annular lock member 64 corresponding to the concaveguide portions 66 are formed as projecting portions 67 projectingradially outward in order to make a wall thickness of resin even. A sidewall 66 a of the concave guide portion 66 comes in contact with a sidesurface 65 a of the convex guide portion 65, so that rotation of theannular lock member 64 is prevented by both the guide portions 65 and66. Outer surfaces of portions of the annular lock member 64corresponding to the concave guide portions 66 are formed as projectingportions 67 projecting radially outward in order to make a wallthickness of resin even. A stopper 68 on which an end portion 65 b ofthe convex guide portion 65 abuts is provided on the concave guideportion 66, and the stopper 68 abuts on the end portion 65 b of theguide portion 65 so that the position of the annular lock member 64 in adirection toward the bottom wall portion 28 b of the collectioncontainer 27 is restricted.

Two inclination projections 71 are provided on an outer peripheralsurface of the collection container 27 so as to be shifted from theconvex guide portion 65 by an angle of 90 degrees in a circumferentialdirection. The inclination projection 71 has an inclination surface 72inclined radially outward toward the bottom portion of the collectioncontainer 27. On the other hand, tongue pieces 73, each inclining upwardand radially inward and contacting with the inclination surface 72, areprovided on an inner peripheral surface of the annular lock member 64 soas to project toward the inside of the annular lock member 64. A portionof the annular lock member 64 which is provided with the tongue piece 73is recessed, and an outer surface of a portion of the annular lockmember 64 corresponding to the recessed portion is formed as aprojecting portion 74.

The tongue piece 73 is made of elastically-deformable resin material andis formed integrally with the annular lock member 64, and a distal endside thereof is elastically deformed so as to displace in a radialdirection. The tongue piece 73 is formed so that its distal end, namely,an inclination distal end is inclined radially inward. Since the annularlock member 64 integrated with the tongue pieces 73 is molded byelastically-deformable resin, an inclination distal end of the tonguepiece 73 can be deformed by a radially outward force. Therefore, whenthe annular lock member 64 is moved in the longitudinal direction towardthe bottom portion of the collection container 27, the distal end sideof the tongue piece 73 is elastically deformed so as to slide along theinclination surface 72 to displace radially outward. A pressing forcetoward an opening end portion of the collection container 27 is biasedto the annular lock member 64 by repulsive force of the elasticallydeformed tongue piece 73. Therefore, when the annular lock member 64 isreleased from a hand of an operator under such a state that the annularlock member 64 has been moved manually toward the bottom portion of thecollection container 27 to a lock release position, the annular lockmember 64 is automatically returned to its original position by thepressing force. Thus, a pressing member which presses the annular lockmember 64 toward the port block 13 is formed of the tongue piece 73 andthe inclination projection 71 having the inclination surface 72.

The projecting portion 67 including the concave guide portion 66 on theinner surface thereof is protruded beyond an end surface of the annularlock member 64 axially outward toward the port block 13, and a protrudedend portion of the projecting portion 67 constitutes a movable sideengagement portion 75. On the other hand, a flange 76 provided on theseparation cylinder 20 is formed with a notched portion engaged with themovable side engagement portion 75, and the notched portion constitutesa fixation side engagement portion 77. As shown in FIG. 9, a lowersurface of the flange 76 constitutes an abutting end surface 78 on whichthe annular lock member 64 is caused to abut, and the fixation sideengagement portion 77 is formed with a first stopper surface 77 a. Onthe other hand, a side surface of the movable side engagement portion 75constitutes a second stopper surface 75 a opposed to the first stoppersurface 77 a.

The annular lock member 63 also has the same shape as the annular lockmember 64, and a guide portion similar to the convex guide portion 65shown in FIG. 10 is provided on an outer peripheral surface of thecylindrical portion 21 of the separation cylinder 20 and an inclinationprojection 71 similar to the inclination projection 71 is providedthereon. A movable side engagement portion similar to the movable sideengagement portion 75 of the annular lock member 64 is also provided onthe annular lock member 63, and the movable side engagement portion isengaged with a fixation side engagement portion provided on the portblock 13.

FIG. 11 is a cross sectional view showing the upper half of a filteraccording to another embodiment of the present invention, FIG. 12 is aperspective view of FIG. 11, and FIG. 13 is an exploded perspective viewshowing a swirl flow generator shown in FIGS. 11 and 12.

The swirl flow generator 32 shown in FIGS. 11 to 13 is configured to jetair in a radially outward direction of the cylindrical blade portion 34to generate swirl flow, which is different from the swirl flow generator32 of the filter 10 shown in FIG. 1 which is configured so as to jet airin a radially inward direction of the cylindrical blade portion 34 togenerate swirl flow.

As shown in the figures, a cylindrical sleeve 81 is provided integrallywith the annular base portion 33 of the swirl flow generator 32, and thesleeve 81 is fitted and fixed to the outside of the discharge pipe 37.The annular base portion 33 is fixed to the discharge pipe 37 by a nut83 screwed to a male screw 82 formed on the discharge pipe 37. Theannular base portion 33 is integrated with the cylindrical blade portion34, and the cylindrical blade portion 34 is composed of a plurality ofblades 35 extending along the sleeve 81 outside thereof in an axialdirection.

In order to supply air from an upper end of the cylindrical bladeportion 34 along the sleeve 81 in the axial direction, the air havingflowed from the primary port 11 into the receiving hole 14, an annularclosing lid portion 38 is arranged inside the receiving hole 14, and aninner-periphery side lower surface of the closing lid portion 38 iscaused to abut on an outer peripheral portion of an upper end of thecylindrical blade portion 34. Notched portions 39 on which the closinglid portion 38 abuts are formed on an outer peripheral portion of theupper end of the cylindrical blade portion 34.

A liquid droplet guiding surface 46 a that is inclined downwardly andradially outwardly from a lower end portion of the sleeve 81 is formedon the annular base portion 33, so that liquid droplets in air guided bythe blades 35 to reach the lower end portion of the cylindrical bladeportion 34 flow along the inclined liquid droplet guiding surface 46 ato drop into the separation chamber 25. Since the dropping position isaway from the discharge pipe 37, liquid droplets are prevented fromentering the discharge pipe 37. In addition, since the inside of thecylindrical portion 21 is formed as a diameter-enlarged portion which isset so that the inner diameter of the cylindrical portion 21 is largerthan the inner diameter of the swirl flow generating portion inside themale screw portion 17, and the lower end portion of the discharge pipe37 is positioned in the diameter-enlarged portion, liquid droplets canbe prevented from entering the discharge pipe 37.

Thus, as the cylindrical blade portion 34, there are the first aspectwhere air flowing in the axial direction is swirled while being causedto flow radially inward, and the second aspect where the air is swirledwhile being caused to flow radially outward.

The present invention is not limited to the above-described embodimentsand may be modified variously without departing from the gist of thepresent invention. For example, though a manual drain mechanism isprovided in the collection container 27 in order to discharge liquidaccumulated in the collection container 27 outside, an automatic drainmechanism or a semi-automatic drain mechanism may be provided in thecollection container.

INDUSTRIAL APPLICABILITY

The filter is used, in a pneumatic system including a pneumatic powersource and a pneumatic device operated by compressed air supplied fromthe pneumatic power source, for removing foreign matters such as liquiddroplets contained in the compressed air.

What is claimed is:
 1. A filter for removing foreign matter contained inair to purify the air, comprising: a separation unit including a primaryport to which the air is supplied, a cylindrical swirl flow generatingchamber communicating with the primary port via a receiving hole locatedabove the swirl flow generating chamber, a separation chamber locatedbelow the swirl flow generating chamber and communicating with the swirlflow generating chamber, and a secondary port causing purified air inthe separation chamber to flow out; a discharge pipe arranged at acentral portion of the swirl flow generating chamber to guide purifiedair to the secondary port; and a cylindrical blade portion formed byarranging a plurality of blades in a cylindrical form, each of whichextends in an axial direction along an inner peripheral surface of theswirl flow generating chamber and inclines in the circumferentialdirection, wherein the air supplied from the primary port and inflowinginto the swirl flow generating chamber in the axial direction is swirledto remove foreign matters contained in the air, wherein the cylindricalblade portion swirls the air supplied from the primary port whileletting the air flow in a radially-inward direction.
 2. A filter forremoving foreign matter contained in air to purify the air, comprising:a separation unit including a primary port to which the air is supplied,a cylindrical swirl flow generating chamber communicating with theprimary port via a receiving hole located above the swirl flowgenerating chamber, a separation chamber located below the swirl flowgenerating chamber and communicating with the swirl flow generatingchamber, and a secondary port causing purified air in the separationchamber to flow out; a discharge pipe arranged at a central portion ofthe swirl flow generating chamber to guide purified air to the secondaryport; and a cylindrical blade portion formed by arranging a plurality ofblades in a cylindrical form, each of which extends in an axialdirection along an inner peripheral surface of the swirl flow generatingchamber and inclines in the circumferential direction, wherein the airsupplied from the primary port and inflowing into the swirl flowgenerating chamber in the axial direction is swirled to remove foreignmatters contained in the air, wherein the cylindrical blade portionswirls the air supplied from the primary port while letting the air flowin a radially-outward direction.
 3. The filter according to claim 1,comprising: an annular base portion which is arranged at a lower end ofthe cylindrical blade portion and fitted to an inner peripheral surfaceof the separation unit; and a closing lid portion arranged between thedischarge pipe and an upper end of the cylindrical blade portion.
 4. Thefilter according to claim 2, comprising: an annular base portionarranged at a lower end of the cylindrical blade portion and fixed tothe discharge pipe; and a closing lid portion arranged between an innerperipheral surface of the separation unit and an upper end of thecylindrical blade portion.
 5. The filter according to claim 3, whereinthe cylindrical blade portion and the annular base portion areintegrally formed.
 6. The filter according to claim 4, wherein thecylindrical blade portion and the annular base portion are integrallyformed.
 7. The filter according to claim 5, wherein notched portions areformed at an upper end portion of each of the blades and the closing lidportion is fitted to the notched portion.
 8. The filter according toclaim 6, wherein notched portions are formed at an upper end portion ofeach of the blades and the closing lid portion is fitted to the notchedportion.
 9. The filter according to claim 5, wherein a liquid dischargegroove is formed between an outer peripheral surface of the annular baseportion and the separation unit.
 10. The filter according to claim 6,wherein a liquid discharge groove is formed between an outer peripheralsurface of the annular base portion and the separation unit.
 11. Thefilter according to claim 3, wherein a first liquid droplet guidingsurface gradually inclined downward in a radially-inward direction isformed to an upper surface of the annular base portion so that liquiddroplets attached to the upper surface of the annular base portion aredropped downward by the first liquid droplet guiding surface.
 12. Thefilter according to claim 3, wherein the lower surface of the closinglid portion is formed in a perpendicular direction to a central axis ofthe separation unit from an outer peripheral portion to an innerperipheral portion or formed to be inclined downward below theperpendicular direction from an outer peripheral portion to an innerperipheral portion.